The present invention relates to orthopedic surgical devices generally, and more specifically, the present invention relates to devices which utilize Kirschner wires in connection with external fixator rings or other devices for positioning bone fragments or for tensioning a bone for accelerating bone length growth.
External fixation devices have been used for many years and are well known in the surgical field and are a common appliance in the practice of orthopedic surgeons for treating trauma, especially of the leg and arm bones. The state of the art was reviewed by Brooker, Andrew F. Jr., M.D., and Edwards, Charles C., M.D., in EXTERNAL FIXATION THE CURRENT STATE OF THE ART, Williams & Wilkens, Baltimore/London 1979. Among the devices currently in use are the Ilizarov external fixator described by F. A. Ilizarov, "Compression Distraction Apparatus," U.S.S.R. Patent No. 538710-3338801 1-28-13, and in U.S. Pat. No. 4,615,338. The Ilizarov external fixator is described along with its applications in a product information bulletin published by Richards Medical Company, 1450 Brooks Road, Memphis, TN 38116. Another external fixator is the Monticelli Spinelli external fixation system marketed by Howmedica, and described in product literature distributed by the manufacturer.
An improved external fixation device was developed by Dr. David A. Fischer, and is described in his Patent No. 4,450,834. The Fischer external fixation device is distributed by Ace Orthopedic Manufacturing, Inc., of Los Angeles, CA. Many other external fixation devices are also known, but the foregoing are sufficient to exemplify the general structure and utilization of such devices.
Generally speaking, the type of fixation device which is under consideration may be described as comprising at least two, and frequently three rings or partial rings which are sized and configured to extend around the body part which is being treated for trauma or to accelerate bone length growth, most frequently in the treatment of trauma. The Fischer device typically comprises two arcuate portions which when connected together through bolts and clamps or other means, form a complete ring encircling the leg, arm, etc., under treatment. The Howmedica device, designed by Jaquet Orthopedie, also utilizes matching arcuate sections which are connected together, although the construction and operation differ considerably from the Fischer device. The Ilizarov device is of a similar construction but uses a different kind of ring construction and configuration.
The external fixation device which is the subject of this application also comprises clamps for pins which may be screwed into the bone fragments, the clamps being connected to the rings in such a manner that by movement of the clamps and the rings, or both, the bone fragments may be aligned to permit proper healing.
Another utilization of external fixation devices of the type which are the subject of this application utilizes Kirschner wires which extend through the bone, or bone fragment, and are clamped at the respective ends thereof on different portions of the ring, typically diametrical portions of the ring, and are held under very strong tension to permit bending of the wire. Kirschner wires require only a very small passage through the bone, and thus are less traumatic than the screws which are sometimes necessary.
The present invention comprises and improved Kirschner wire clamping and tensioning device. A Kirschner wire may be described simply as an elongate wire of biologically compatible metal or alloy which is relatively rigid. For convenience, reference has been made to such wires as the Kirschner wire, but any wire under tension extending through a bone or a bone fragment may be utilized in connection with the present invention.
The present invention provides a clamp for rigid tensioned wires in external fixation devices which permits tensioning to a desired and known degree, locking without loss of tensioning, and without the necessity for additional torque wrenches or other torquing devices which measure the amount of tension on the wire.